The invention pertains to a tire positioning system incorporated into a tire mounting assembly line whereby the wheel and its associated tubeless tire are angularly oriented to each other in a predetermined manner prior to tire inflation.
In the high production assembly of wheels and tires conveyor lines are employed having a plurality of processing stations wherein the wheel and tire are processed toward final assembly. Basically, such a wheel and tire assembly line includes a primary conveyor to which a wheel and tire are separately conveyed upon pallets or other conventional material handling apparatus. The tire is preliminarily laid upon the wheel, and at succeeding stations the tire may be soaped or otherwise lubricated prior to being pushed over the wheel rim whereby the tire beads will be located within the confines of the wheel rim. Usually, the next step is to inflate the tire which is accomplished by placing an air chamber against the wheel sidewall while holding the sidewall away from the wheel rim. Compressed air is rapidly introduced into the tire causing the sidewall to sealingly engage the wheel rim completing inflation. Thereupon, the wheel and tire assembly is completed, and if desired, other stations producing balancing, or secondary operations may be included.
In the evaluation of tire and wheel running characteristics it has long been appreciated that balancing of the assembled tire and wheel is necessary to produce optimum tire wear, smooth operation, roadability, safety and optimum riding characteristics. Accordingly, assembled wheels and tires are normally balanced by the addition of weights to the wheel rim to equalize the distribution of wheel and tire weight about the tire axis. The weighting, and the determining of the location of the weights, may be done while the wheel is in a dynamic or static condition, usually dynamic balancing achieving the most accurate results. Under dynamic balancing lateral, as well as radial, imbalances can be detected and compensated for.
It has further been appreciated that harmonic forces within tires occur which affect tire wear, riding comfort, etc., and imbalance occurring within the wheel, itself, create problems under rapid wheel rotation. Accordingly, as both the tire and wheel, as manufactured, do not have uniform weight distribution it is desirable to preliminarily orient the wheel and tire after initial assembly, and prior to tire inflation, to orient those portions of the wheel and tire most likely to create imbalance whereby during the final balancing of the wheel assembly a minimum of weights and simplified balancing procedures can be utilized. Apparatus has been developed whereby the maximum tire radial first harmonic force, called a "high point", can be identified prior to the tire being mounted upon a wheel, and the point upon the wheel wherein minimum average radial run out occurs, called the "low point", can be identified by the wheel valve stem hole. By marking the tire high point and the wheel low point with indicia prior to assembly and orienting the high and low point to each other relative to the wheel axis after assembly final wheel-tire balancing is facilitated. Previously, such preliminary orientation of the wheel and tire prior to inflation, if accomplished, was done manually and in a haphazard manner. With the apparatus of the invention such wheel and tire orientation is automatically achieved efficiently and accurately without human operation or supervision.
It is an object of the invention to provide a method and apparatus for orienting predetermined locations of a tire relative to its wheel prior to tire inflation wherein the sensing of predetermined positions upon the wheel and tire automatically occur, and the wheel and tire are rotated relative to each other to angularly orient such predetermined locations.
A further object of the invention is to provide a method and apparatus for orienting an uninflated tubeless tire relative to its wheel by automatically sensing the location of light responsive indicia defined on the tire and wheel, and wherein the sensing of such indicia produces electronic signals which are stored and analyzed to control apparatus for relatively rotating the tire and wheel to orient the indicia to each other in a predetermined manner.
Another object of the invention is to provide automatic tire and wheel positioning and orientation apparatus wherein the angular relationship of tire and wheel indicia relative to the wheel axis is electronically sensed and analyzed and the tire and wheel are then rotated relative to each other in a direction minimizing the necessary relative tire and wheel movement to orient the indicia in a predetermined manner.
An additional object of the invention is to provide automatic wheel and tire positioning apparatus wherein the wheel and tire may be rotatably oriented to each other in a predetermined manner, and the apparatus may be incorporated into conventional wheel and tire mounting and assembling systems compatible with known tire mounting apparatus.
In the practice of the invention the tires to be mounted, usually radial passenger car tires, although not limited thereto, are placed upon sensing equipment which weighs and tests the tire to locate the circumferential location of the maximum first harmonic force. Once this "high point" portion of the tire is determined indicia indicating such position is applied to the tire, preferably upon the sidewall, and in the preferred embodiment the indicia comprises a reflective mark or patch capable of reflecting ultraviolet light. Likewise, the wheel to which the tire is to be mounted also receives ultraviolet light reflecting indicia at its minimum average radial run out point, i.e. "low point", which normally coincides with the tire stem hole. When the wheel and its tire are preassembled the indicia applied thereto are visible from a common side of the wheel and tire. Usually, the axes of the wheel and tire, after preliminary assembly, are vertically oriented, and the indicia appears upon the upper side of the tire and wheel.
After the tire has been placed between the rims of the wheel the wheel is indexed on a conveyor to a sensing station and the wheel oriented coaxially with a sensing axis. Ultraviolet light sensing means rotate about the sensing axis and upon the sensing means separately sensing the location of the tire and wheel indicia electronic signals are produced which are received, stored and analyzed by computing means. As the sensing means rotates about the sensing axis the sensing of the wheel and tire indicia produces signals indicative of the angular relationship of the wheel and tire indicia relative to the wheel axis, and the computing means analyzes such data to produce a control signal for regulating subsequent relative rotation between the tire and wheel.
After sensing of the indicia the wheel and tire are transferred a short distance to another work station without relative rotational movement occurring between the wheel and tire. At this station the wheel is oriented coaxial with an orientation axis and relative rotation between the wheel and tire occurs as determined by the control signal from the computer means. While relative rotation between the tire and wheel may be achieved by rotating the wheel within the tire, or rotating the tire upon the wheel, in the preferred embodiment the tire is raised slightly with respect to the wheel to minimize frictional engagement therebetween, and is rotated in that direction under the influence of the computer means which most quickly orient the wheel and tire indicia in a predetermined manner, usually with a 0.degree. deviation relative to each other about the wheel axis.
Once the wheel and tire are angularly oriented as desired they are transferred to an inflation station which may be of conventional construction, without relative rotation existing therebetween, and upon inflation of the tire the desired rotational orientation of wheel and tire will be achieved.
In the practice of the invention the sensing of the wheel and tire indicia and the relative rotation of the wheel and tire is automatically produced by means of switches, interlocks, and other known control apparatus and by locating the sensing and orientation axes within the regular tire mounting conveyor the aforedescribed wheel and tire positioning apparatus can be achieved without extensive modification to existing tire mounting systems.